Animal Biodiversity and Conservation 34.1 (2011) 179 Effects of sea bass and sea bream farming (Western Mediterranean Sea) on peracarid crustacean assemblages V. Fernandez–Gonzalez & P. Sanchez–Jerez Fernandez–Gonzalez, V. & Sanchez–Jerez, P., 2011. Effects of sea bass and sea bream farming (Western Mediterranean Sea) on peracarid crustacean assemblages. Animal Biodiversity and Conservation, 34.1: 179–190. Abstract Effects of sea bass and sea bream farming (Western Mediterranean Sea) on peracarid crustacean assemblages.— Benthic soft–bottom assemblages are good indicators of environmental disturbance, such as coastal aquaculture, considering their rapid response in terms of diversity and abundance. The aim of this study was to evaluate the response of peracarid assemblages to the release of waste from coastal farming as these organisms play an important ecological role. Abundance and species richness did not show significant differences between farm and control localities but did show a high spatial variability at the two studied scales. Non–metric multi– dimensional scaling (MDS) analysis showed a separation between farms and controls, indicating that peracarid assemblages are modified as a result of aquaculture activities, and some species such as Ampelisca spp. showed statistical differences. Peracarids, at both species and community level, may therefore be applied as helpful indicators to assess benthic effects of coastal farming. Key words: Benthos, Aquaculture, Impact, Indicators, Management, Sustainability. Resumen Efectos del cultivo de la lubina y la dorada (Mediterráneo occidental) sobre las comunidades de crustáceos peracáridos.— Las comunidades bentónicas de fondos blandos son buenas indicadoras de perturbaciones ambientales, tales como la acuicultura costera, teniendo en cuenta sus cambios relativamente rápidos en términos de diversidad y abundancia. El objetivo del presente estudio es evaluar la respuesta de las comu- nidades de peracáridos a la liberación de desechos de las instalaciones de acuicultura costeras, dado el importante papel ecológico de estos organismos. La abundancia y la riqueza de especies no mostraron dife- rencias significativas entre áreas con impacto y de control, pero si una importante variabilidad espacial a las dos escalas estudiadas. El análisis no métrico de escalas multidimensionales (EMD) mostró una separación entre las piscifactorías y los controles, lo que indica que las comunnidades de peracáridos se ven modificadas como resultado de las actividades relacionadas con la acuicultura, donde algunas especies, como Ampelisca spp. mostraron diferencias significativas. Por lo tanto, los peracáridos, tanto a nivel de especie como de comunidad, pueden ser utilizados como buenos indicadores para evaluar el efecto de la acuicultura sobre el fondo marino en ambientes costeros. Palabras clave: Bentos, Acuicultura, Impacto, Indicadores, Gestión, Sostenibilidad. V. Fernandez–Gonzalez & P. Sanchez–Jerez, Dept. of Marine Sciences and Applied Biology, Univ. of Alicante, P. O. Box 99, 03080 Alicante, España (Spain). Corresponding author: Victoria Fernandez–Gonzalez. E–mail: [email protected] ISSN: 1578–665X © 2011 Museu de Ciències Naturals 180 Fernandez–Gonzalez et al. Introduction directly assessing the effects of coastal farming on peracarid assemblages in the Western Mediterranean. Aquaculture activities have increased greatly in coastal Consequently, to evaluate the environmental impact of marine areas during the last decades (Mazzola et al., fish farming using peracarid assemblages we applied 2000; Mirto et al., 2000; Borja, 2002; Klaoudatos et a multi–control impact design with a spatial replica- al., 2006; Sánz–Lázaro & Marín, 2006; Sutherland et tion at different scales to understanding the natural al., 2007; Grego et al., 2009). This situation has been spatial variability with regards to the influence of the induced by progressive advances in cage building, fish farming activity. which facilitated mooring of cage farms and their es- tablishment on relatively deep bottoms and exposed sites (Maldonado et al., 2005). Since floating cages for Material and methods intensive aquaculture started to appear, general concern has increased for the potential impact of this activity on Study area and sampling method marine ecosystems (Mazzola et al., 2000; Mirto et al., 2000; Klaoudatos, 2002; Sánz–Lázaro & Marín, 2006; Three Mediterranean fish farms located east off the Sutherland et al., 2007). These effects include: organic coast of Guardamar del Segura (Alicante, SE Spain: enrichment, derived from excess of uneaten food and 38° 5' 45.88'' N; 0° 36' 15.84'' W) were selected for the fish excretions, chemical pollution, related with medicines study. All farms cultured sea bream (Sparus aurata) and antifouling products, genetic effects and introduction and sea bass (Dicentrarchus labrax). In addition, of non–native species, resulting from both the escapes three control zones in the same area were also se- and alterations of adjacent benthic and pelagic fauna lected. They were located at least 1.5 km away from (Borja, 2002; Dempster et al., 2002; Macías et al., the farms to minimize the potential interactions with 2005; Holmer et al., 2007; Borja et al., 2009). From dispersed farm wastes. Samples were collected in among these possible impacts, the most evident effect March 2009. Regarding fish farm–impact monitoring, of fish cages on seabeds is the accumulation of orga- punctual sampling can be relevant, because if impor- nic matter, which generates significant changes in the tant environmental and biotic parameters are affected, chemical, physical and biological characteristic of the the differences between controls and farms should sediment (Karakassis et al., 2000; Mirto et al., 2002; be detectable at any time (Maldonado et al., 2005). Klaoudatos, 2002; Maldonado et al., 2005; Martí et al., To study benthic community, three random repli- 2005; Marbà et al., 2006; Sánz–Lázaro & Marín, 2006; cates were collected at each site using a Van Veen Lampadariou et al., 2008; Grego et al., 2009; Mirto et grab (0.04 m2), sieved in seawater through a 500 µm al., 2010). These effects can be noted within a range of mesh and preserved in 4% formalin. In the laboratory, tens to hundreds of meters (Mazzola et al., 1999; Mirto the peracarids were separated, identified at the lower et al., 2002; Aguado–Giménez & García–García, 2004; possible taxonomic level and counted. Tomassetti et al., 2009). An additional sample was collected at each location Additionally, the increase of organic matter and sedi- for sediment analysis. Sediment particle size was ment structure is affected by silting, increased oxygen determined by the wet sieve method, and organic demand, anoxic sediment generation and toxic gases matter content by incinerating a known dried sample (Borja, 2002; Martí et al., 2005). All of these effects in a muffle furnace at 450°C for 4 h (Buchanan, 1984). could modify the structure and characteristics of the benthic assemblages (Mazzola et al., 1999, 2000; Data analysis Mirto et al., 2000; Maldonado et al., 2005; Martí et al., 2005; Marbà et al., 2006; Klaoudatos et al., 2006; We tested the differences of peracarid assemblages Lampadariou et al., 2008). Due to their small size, between control areas and farms using both univariate high abundance, direct relation with the sediment, and multivariate statistical analyses. high turnover and fast response time to perturbations, Benthic fauna are presently utilized as a useful indica- Univariate analysis tor to detect environmental changes due to pollution (Boyra et al., 2004; Sutherland et al., 2007; Grego et We analysed the number of species and total abun- al., 2009; Fabi et al., 2009). Crustaceans are one of dance of the peracarids, and abundance of the most the most important taxa in the benthic fauna, in terms important species using analysis of variance (ANOVA). of diversity and abundance. Several groups belonging The experimental design incorporated three factors: to this taxon are very ecologically sensitive organisms. control/farm (fixed and orthogonal with two levels), As a consequence, a high number of species appear locality (random and nested in treatment, with three as good indicators of different environmental conditions. levels), and site (random and nested in Locality, with Several studies have effectively applied copepods two levels). Prior to ANOVA, heterogeneity of varian- harpacticoids (e.g. copepods–nematods index; Ra- ce was tested with Cochran’s C–test and data were ffaeli & Mason, 1981), ostracods (Ruiz et al., 2005), √ x + 1 transformed in cases where the variances were cumaceans (Corberá & Cardell, 1995) and amphipods significantly different, with P < 0.05, and log (x + 1) (Conradi et al., 1997; Gómez–Gesteira & Dauvin, transformed where the variance was still heteroge- 2000; Sánchez–Jerez et al., 2000; Guerra–García & neous (Underwood, 1997). Post hoc Student–Neuman García–Gomez, 2001) for assessing different types of Kuels (SNK) tests were used if significant differences environmental impacts. However, there are no studies were found. Animal Biodiversity and Conservation 34.1 (2011) 181 Control Farm 100 14 90 12 Organic matter (%) 80 70 10 60 8 50 6 40 30 4 20 2 10 Particle size distribution (%) 0 0 F1–S1 F1–S2 F2–S1 F2–S2 F3–S1 F3–S2 C1–S1 C2–S1 C2–S2 C3–S1 C3–S2 C1–S2 Mud % Fine sand % Medium sand % Coarse sand % OM Fig. 1. Granulometric structure of sediment at the studied zones, expressed as the relative abundance (dry weight